1. Field of the Invention
The invention relates to a method for detecting chattering that occurs when a workpiece is machined by a machine tool.
2. Discussion of Background
In order to suppress chattering, it is important to detect occurrence of chattering and its frequency. Japanese Patent Application Publication No. 2000-210840 describes a chattering detection method in which whether chattering is occurring is determined based on a frequency of a vibration. Japanese Application Publication No. 2000-233368 describes determining whether chattering is occurring based on the level of a vibration and the degree of a change in the vibration over a given period of time.
According to Japanese Patent Application Publication No. 2000-210840, chattering is detected through comparison between a reference vibration frequency, which is set and stored in advance, and a chattering frequency. However, a chattering frequency varies depending upon combinations of various tools and workpieces. Therefore, if chattering having an unpredictable frequency occurs, the chattering may not be detected.
According to Japanese Patent Application Publication No. 2000-233368, chattering is detected based on the level of a vibration and the degree of a change in the vibration over a given period of time. However, a vibration level varies depending upon the machining conditions and the state of a cutting edge of a tool. Therefore, chattering vibration detection may not be stably performed.